When on inverter am I using the batteries?

msturtz wrote:

dougrainer wrote:
What Mr Wizard states is TRUE. But not for the reason he stated. You ALWAYS disconnect Shore Power before starting the Genset AND turn off the Interior MAIN Breaker/s. You NEVER Transfer with a LOAD. This prevents arc'ing of the Transfer relay points, which causes wear and premature failure. Read posts from people that state they have multiple failures of Transfer boxes. Caused by transferring under load. You also Turne Loads OFF when turning the Genset OFF. Some Transfer boxes close a relay when connecting either Shore or Genset. Some, the Shore relay stays closed. Unless you know for sure which style you have always have NO LOAD when engaging various Power supplies. Doug

I'm sorry to have to disagree with you. Proper transfer switches are designed to switch "under load". I have experience with RV type transfer switches but also automatic emergency generator systems. These systems routinely transfer "under load" by definition. The same is true for UPS systems which I have specified in my job. While it is true that the relays can wear out over time due to arcing that should be minimal as these devices are specifically designed to be operated in this manner. In fact, properly designed and implemented transfer switches should be completely transparent to any connected system i.e. the dropout should be less than a fraction of a phase cycle. The capacitors in most equipment should bridge that short of a mid cycle dropout. More advanced transfer equipment common in UPSes can actually use phase drift to wait until both sources are in phase prior to switching over. RV switch gear usually isn't that advanced unfortunately. Bottom line is with a properly wired and designed system (RVIA and NEC codes) in no case should anything bad happen if you have all three sources of power available at the same time. It CAN happen with a mis-wired coach or with defective equipment however the underlying problem MUST be corrected rather than masking it by turning off all sources of power prior to switching over. All this said if a person wants to cut all power and then start up the new source go ahead but it will only be a marginal at best savings on the transfer switch(s).